Wireless network connecting to another computer switch then internet

Heymy brother changed some settings and now my wireless connection connects to his computer as switch then to the internet this seems to of slowed my internet connection. he did this just to annoy me. the modem with router is in his room so he is cabled and I am connected wirelessly from my room. I have taken screenshots of the network maps so you can understand the situation which I can upload here(if possible) or e-mailto whoever needs it. in the network map what should happen is that I should be connected to my access point the got to "Gateway" then to the internet. but what actually happens is that I connect to access point then to my brothers computer then to switch then to "Gateway" and internet. Thanks In advance